Magnetically operated sensing device



Nov. 28, 1961 J. J. LA ROCCA MAGNETIC/ALLY OPERATED sENsING DEVICE 2 Sheets-Sheet l Filed Dec. 14, 1959 n; A m0 uuwn .kzoo MR T N @zu oz z5 oz WA HW N uw 1L f J. 6 s A MN m M M W Nov. 28, 1961 J. J. LA ROCCA MAGNETICALLY OPERATED sENsING DEVICE 2 Sheets-Sheet 2 Filed Dec. 14, 1959 NM MM.

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INVENTOR. JAMES J. LAROCCA BY ww@ 1 @M United States Patent O i 3 011,036 MAGNETICALLY OPRATED SENSING DEVICE James J. La Rocca, Matteson, lli., assigner to Continental Can Company, Inc., New York, NX., aqcorporation of New York v y rFiled Dec. 14, 1959, Ser. No.l 85,288 3 Claims. (Cl. 20G-87) The present invention relates to a magnetically operated device for the detection of the absence of tferrous metal articles from a procession of such articles travelling in a predetermined path.

More specifically, the invention relates to a magnetically oper-ated sensing device which detects the absence of can bodies in a procession of equally spaced ferrous metal can bodies being delivered along a conveyor into a machine which appl-ies an end to the can bodies. When these is an absence of a can body in the procession, it is undesirable for the can end supply means of the can end applying machine to deliver a can end to the can end delivery station of the machine when no can body is present for the can end to be seamed on to. A can end thus delivered is wasted and may become jammed in the machine where it can do damage.

Meansfor sensing or detecting the absence of can bodies in a procession of can bodies is old, mechanical means for detecting the absence of a can body being described in Patent No. 2,755,763. In this patent, the detecting device is comprised of a rod or shoe which rides against a side of the procession of can bodies as they are being fed into a canA end applying machine. Whenever a can is absent from the procession of can bodies, the rod orshoe is spring urged a slight distance into the empty space and a switch actuator attached to an arm supporting the shoe is caused to move by virtue of the displacement of the shoe from its normal position so that the switch actuator actuates an electrical switch which in turn causes the actuation of. a no-can 11o-end device located on the can end applying machine which prevents the delivery of a can end at the appropriate time when the empty space is at the can end deliver-yr station of the machine. lt has been found from eX- perience that such mechanical detecting devices leave much to be desired, as the detecting shoe or rod may scratch or den-t the can bodies as they traverse the detecting station as there is an actual physical contact between the shoe or rod and the can bodies. In order to o er come this deciency in mechanical detecting devices, magnetically operated devices were resorted toas magnetic devices do not require kany phys-ical Contact with the ferrous metal can bodies as they traverse the detecting station on the conveyor leading to the can end applying machine. One such magnetically operated detecting device is shown in Patent No. 2,755,762. The magnetic detecting device shown in this patent is generally satisfactory and efficient in operation, however, it is more complicated than desired, is relatively expensive, and due to the many parts making up the detecting unit, it is prone to require adjustment and maintenance from time to time.

The presently disclosed magnetically controlled sensing device is much simpler than either of the devices mentioned in the above referred to patents. ln View of its simplicity, it is very inexpensiveto fabricate, is practically ICG position to its closed position whenever there is an empty,

space due to a can body being missing `from the procession of can bodies as they traverse the path adjacent the space between the magnet and switch, said actuation of the switch being caused by magnetic flux from the magnet being diverted toward the switch due to the absence of the can body which normally would absorb the ux,

and electrically operated means associated with the switchrv and ioperated by the positioning of theswitch contacts.y

' yIt is a further object of the invention to provide a detecting device of the character described comprising a permanent magnet arranged in iixed position closely adjacent the path of can bodies travelling in processional order, and having a magnetically operated switch located adjacent the magnet at such a distance therefrom, that when the procession of can bodies is uninterrupted, sutlcient flux from the magnetic field extending between the magnet and switch will be absorbed byat least one can tion; and means electrically connected to the switch to silence the delivery of a can end by the can end supplying means of a can end attaching machine when the switch contacts are caused to close due to the absence of a can body in the procession of can bodies when the space left by the missing can body is in position to receive a can end from the can end supplying means.

.A11 additional objectof the invention is to provide a` detecting device of the character described associated with a no-can no-end control device having timing means included in its circuitry, said timing means being necessary for fthe proper operation of the device when the can bodies in the procession are spaced far apart so that the switch contacts are caused to open and then close by the passage of each can body in the procession,

With the above and other objects in view that will here'- inafter appear, the nature of the invention will be more clearly understood `by reference to the following detailed description, the appended claims and the accompanying drawings which show schematically a preferred forni ofthe invention in FIG. l and an alternate form of the invention in FIGURE 2 which maybe resorted tov when the can bodies in the procession are spaced a considerable distance apart.

Referring to the drawings and to FIG.- l in particular,

, can bodies 10 are moved in a predetermined path in evenly lspaced relationship by means of my conventional conveying means such as a conveyor belt` 111.- The di `4 rection of travel of the can bodies is indicatedby therarrow 12. The can bodies are fed into a conventional can end applying machine (not shown)` having associated therewith a conventional no-can no-e'nd controldevice 13 one type of which is shown` in Patent No.f2,755, 762. The no-can nor-endk control device is/arr'anged iii series with a magnetically operated' switcli I4 by r'ear'lsV oef a wire 15 which extends from the line terminal 16: to one ofthe binding posts 17 on theV switch 14; Another wire 18 connected to the other binding post 1`9l on the switch 14 terminates in theno-c'an no-endc'on'trol" deduced in voltage from the usual volt house' current f vice 13'. Another wire 26 leads from the `nof-can rrd-"endr Patented Nov. 28, 19617,-

by means of a transformer 22. A switch 23 may be interposed in the circuit to render the no-can no-end control device inoperative, if it is desired. The novel device for sensing the absence of a can body on the conveyor from the procession of can bodies is indicated generally at 24, and is comprised of previously mentioned magnetically operated switch 14 and a rectilinear bai magnet 25 having its magnetic poles at each of its ends. It is preferable that switch 14 and magnet 25 be cast into a plastic housing 26. The magnet is preferably iixedly located closely adjacent the walls of the can bodies as they traverse the conveyor with its major axis being parallel with the direction of travel of the can bodies. Also, it is preferable that the switch 14 have its major axis coincide with the major axis of the bar magnet so that the magnet and the switch are co-extensive. There is a space S between the end of the switch closest the magnet and the adjacent magnetic pole, said space being of predetermined length for proper operation and set before the switch and magnet are cast into the plastic housing.

The proper spacing S between the magnet and switch in each individual case may vary due to differences in strength of the magnet and also due to slightly different characteristics between individual switches. The switch is spaced from the end of the magnet a distance sutiicient so that when there are no can bodies near; the contacts 27 and 28 of the switch will be caused to just close, it being necessary to move the magnet away from the switch only a slight amount to cause the contacts 27 and 28 to again open. When this adjustment has been made, the unit is placed in position adjacent the path of the can bodies so that the magnet is in close proximity to the can body walls. During the normal passage of can bodies there should always be at least a portion of a can body substantially adjacent the space S between the magnet and switch and under this condition, the field of iiux extending from themagnet to the switch will be diverted toward the adjacent can body and suflicient ux will be absorbed by the can body to weaken the field between the switch and magnet sufliciently to cause the contacts 27 and 28 of the switch'to open. The weakening of the field from the magnet toward the switch is equivalent to the weakening of the iieldfrom the magnet toward the switch when the magnet is moved away from the switch the slight amount necessary to cause the contacts of the switch to open. The distance S between the switch and magnet may vary from a fraction of an inch to several inches by selecting magnets of varying strength. It is important that the space between the switch and magnet be selected to correlate with the normal spacing between the canbodies so that during the passing of the canbodies, there will always be at least a portion of a canbody substantially adjacent the space between the switch and magnet to maintain the lield extending from the magnet to the switch in a weakened condition and thus maintain the switch contacts open. When however, there is a space in the procession of can bodies caused by the absence of one or more canbodies, there will be no weakening of the field between the magnet and switch when the empty space is adjacent the space between the magnet and switch to maintain the contacts 27 and 28 of the switch 14 in their open position and the contacts will be caused to close due to the increase in field strength from the magnet toward the switch. The switch preferred is of standard make and is of a type described in Patent No. 2,319,937, and no claim to the switch itself is made. The switch components are preferably mounted in a glass or plastic housing 29, and consist of two resilient ferrous metal strips or arms 30 and 31 mounted in substantially parallel spaced relationship and being coextensive with their furthermost end portions being extended through the housing 29 with the end portion of the arm 30 having the binding post 17 attached thereto and the end portion of the arm or strip 31 having the binding post 19 attached thereto. Contact point 27 is attached to the innermost end of the arm 30 so as to be adjacent and facing the innermost end portion of the arm 31 in face-to-face relationship with the contact point 28. In the normal unmagnetized condition of the switch, the contact points 27 and 28 are spaced slightly apart so that there is no contact between them. However, when a pole of the magnet 25 is placed sutiiciently close to the outermost end of the arm 30, magnetic flux will be absorbed by the arm 3l) which as stated before, is ferrous metal so that the arm 3d in effect becomes a magnet, and a magnetic attraction is set up between the arms 30 and 31 causing them to bend slightly to close the contacts 27 and 28. When the magnet 25 is moved away from the end of the arm Sil a sullicient distance to weaken the magnetic iield adjacent the arm 30, the magnetic properties imparted to the arm 30' by the magnet are diminished sufficiently so that the arms 3i@ and 31 spring apart again due to their resiliency and the points 27 and 28 are caused to open thereby. As explained before, the strengthening or weakening of the magnetic field extending between the switch and the magnet is also accomplished by the presence or absence of a continuous procession of can bodies on the conveyor.

In order to prepare the presently disclosed no-can sensing device for operation, when 4it is used in connection with a no-can 11o-end control device mounted on a can end attaching machine, as shown in FIG. l of the drawings, the device 24 after having the spacing S between the magnet and switch properly adjusted is brought into close proximity to the path of the canbodies as they are fed into the can end applying machine. If the plastic casing 26 is of transparent material, and also if the switch housing 29 is of glass or other transparent material, and canbodies 10 are arranged in processional order on the conveyor, the switch contacts 27 and 28 will be observed to open when the magnet has been brought close enough to the can body side walls to render the device 24 operable. Once the device is in operable position along the path of the can bodies, it may be xedly mounted by any suitable means. The wires 15 and 1S are then attached to the binding posts '17 and 19 respectively, after which 4the switch 23 is closed to supply the necessary electrical energy to operate the no-can no-end control device. The can end applying machine and also the conveyor supplying the can end applying machine with can bodies is now started and the can bodies are now supplied in equally spaced processional order to the can end applying machine. As long as the supply of can bodies is uninterrupted, the contacts 27 and 28 of the switch 14 will remain in their open position rendering the no-can no-end control device l13 inoperative to prevent the subsequent delivery of ends to the can bodies after they have passed into the machine. However, when a can body is missing from the procession of can bodies travelling along the conveyor into the can end applying machine, the contacts 27 and 28 will be caused to close at the time when the space corresponding to the missing can body is disposed adjacent the space S between the magnet and switch. The closing of the contacts 27 and 28 creates an electrical circuit from the transformer 22 through the switch 23, wire '15, binding post 17, arm 30, contacts 27 and 28, arm 31, binding post J9, wire 18, through the no-can no-end control device 13, and out through wire 20 through switch 23, back to the transformer 22. The circuit thus completed, actuates the no-can no-end control device 13 to prevent the delivery of a can end at the time the empty space arrives in the machine at the can end delivery station thereof so that no can end will be delivered into the empty space.

Resumption of the normal feeding of the can ends by the can end applying machine will take place when the next can body following the empty space on the conveyor arrives at a position adjacent the space S between the magnet and switch to divert llux in the lield between the magnet and switch into itself thus causing the contacts 27 and 28 to resume their normal open position.

d The breaking of the electrical circuit through the contacts 27 and 2S thus renders the rio-can no-end control device inoperative to prevent the normal delivery of can ends by the can end applying machine. y

lIn certain instances it is impractical or impossible to have the ferrous metal objects, such as canbodies, in closely spaced order, and in such instances, the switch 14 will close between can bodies sending an undesired signal to the no-can ynoeend device that a can body is missing from the procession. In order to overcome this diiiiculty, the arrangement shown in FIGURE 2 is resorted to. In this arrangement, the no-can no-end control device 13 has incorporated therein, a timing device designated generally at 35 comprised of a cam 36 driven in timed relationship, by any desirable means, with the conveyor 11. The cam 36 operates an electrical switch 37, one side of which is connected to the circuitry of the no-can no-end control device by wire 3S', the other side being similarly connected into the circuitry of the no-can noend device by means of wire 39. The operation of the switch 37 is timed so that it will be closed only when a can body is adjacent the sensing device generally designated at 214. When switch 37 is closed and the switch 14 of the sensing device 24 is open due to the presence of a can body adjacent the sensing device 24', no circuit will be formed through the no-can yno-end control device to render it operable to prevent an end from being delivered. If, on the other hand, there was no can body adjacent the sensing device 24 when switch 37 was closed, then switch 14 would be closed at the same time and a circuit would be completed through the| no-can no-end control device to render it operative to prevent the feeding a can end into the empty space corresponding to the missing can body when the space arrived at the can-end delivery station of the can end applyingfmachine. When the sensing device 24 is disposed between the widely spaced can bodies on the conveyor 11the contacts of the switch 14 will be closed due to no weakening of the field extending from the magnet to the switch. In order to prevent the operation of the no-can no-end control device at this time, the switch 37 will be cammed open to break the circuitry through the no-can noend control device 13 to render it inoperative at all times other than when a can body or the space corresponding to a missing canbody, is adjacent the sensing device 24'.

Also, itis pointed out at this time that it is not necessary to arrange the magnet 25 of the sensing device 24' with its longitudinal axis parallel with the direction of travel of the conveyor 1'1 and the magnet 25 may be arranged as shown with its poles v'adjacent to and spaced S distance from the ends of the arms 30 and 311 projecting from the switch housing. This arrangement creates a more compact grouping resulting in the detecting unit 24 being shorter in length than .the detecting unit 24 of FIG. 1.y The arrangement of the sensing devices 24 and 214' are interchangeable .in the embodiments of the invention shown in FIGS. 1 and 2.

If desired the sensing units 24 or 24' may be readily adapted to be utilized in combination with a can-counting device merely by replacing the no-can noend control device 13 with an electrically actuated counting device (not shown) of standard design. When so used, it is desired that the passing of each can body will cause the contacts of the switch 14 to open after which they will close between can bodies, and since it is desired that such opening and closing of the contacts be registered by the counting device, it is unnecessary to use the timing device 35 in such case.

While preferred forms of the invention have been shown for purposes of illustration, yitis to be clearly understood that various changes in the detailsof construction and arrangement of parts maybe made without departing from the spirit and scope of the invention as delined in the appended claims.

and moving along a predetermined path comprising: a

permanent magnet iixedly positioned adjacent said path; a magnetically operatedV electrical switch located on the `same side of said path as said permanent magnet'and adjacent said permanent magnet and spaced therefrom, said `switch being operated by the magnetic iield extending from the magnet to the switch to assume a first position when an object is missing from the procession on said path adjacent the space between the magnet and switch and to assume a second position when the path has a continuous supply ot equally spaced ferrous metal objects, said switch being operated by a break in the procession of said objects caused by the absence of an object when the space left by the absent object is adjacent the space between the magnet and` switch causing the flux normally absorbed by the missing object to be diverted toward the switch to render it operative to resume its first position; and electrically operated means associated with the switch and operated by the positioning of the switch from its second position to its first position.

2. A device responsive to the absence of ferrous metal objects from a procession of such objects equally spaced and moving along a predetermined path comprising: a permanent magnet adjacent said path; a magnetically operated electrical switch on the same side of said path as said permanent magnet and located adjacent said permanent magnet and spaced therefrom, said switch being operated by the magnetic field extending between the magnet and switch to assume a rst position when no object ispresentadjacent the space between the magnet and switch and to assume a second position due to the divertf ing of the magnetic field away from the switch when ank object is adjacent the space between the magnet and switch, the switch going from its -irst position to its second position back to its tirst posiiton each time an object traverses the path adjacent the space between the magnet and switch; and electrically operated means Velectrically connected to the switch and operated when the switch is in its lirst position due to the absence of an object adjacent the space between the magnet and switch and timing means associated with the electrically operated means to render it quiescent at times when, due to the normal spacing of the objects, no object is present adjacent the space between the magnet and switch.

3. A device responsive to the absence of ferrous metal objects from a proces-sion of such objects equally spaced and moving along a predetermined path comprising: al

permanent magnet tixedly positioned adjacentvsaid path; a magnetically operated electrical switch on the same side of said path as said permanent magnet `and Xedly located adjacent to and spaced from said permanent magnet, said switch being operated by the magnetic eld exe tending between the switch and the magnet to assume a lirst position when no said object on said path is adjacent the space between the switch and the magnet and to assume a second position when an object is present adjacent the space between the switch and the magnet to divert the magnetic eld away from the switch and electrically operated means associated with the switch and responsive to the operation of the switch from one to the other of its positions.

y2,260,771 Buccicone et al. Oct. 28, 1941 2,579,922 Goldsworthy Dec. 25, 1951 `2,667,631 Schaurte Jan. 26, 1954 

